Correction the diffuser has again appeared in its full guise in FP1, we all make mistakes…!
Incidentally McLaren arrived with major revisions around the rear of their car. firstly the diffuser shown in the pitlane for scrutineering was devoid of the upper deck bodywork that extended to the beam wing. this slotted panel effectively stretched the diffuser into a longer and higher device for more dowforce. While the diffuser below this panel is the same version as McLaren ran late in their testing programme. above the diffuser the crash structure and slotted beam wing remain the same, but the added duct to vent the oil cooler has gone.